Mouth ulcers – everything you need to know

by | Aug 19, 2022


Mouth ulcers are also referred to as canker sores and aphthous stomatitis which are small blisters or lesions that develop in the mouth. While there is no definite cause for mouth ulcers there are a number of factors such as injuries and allergies that cause you to develop mouth ulcers.

What are Mouth Ulcers?

Mouth ulcers are small wounds or lesions that occur only in the soft tissues of the mouth such as on your gums or inside your cheeks. You can identify mouth ulcers if you find painful sores on the skin lining your mouth. You will find the skin around the sores is swollen and that you feel pain when chewing food or brushing your teeth. Sour, salty and spicy foods will irritate the sores which will look whitish, yellow or grey in the centre surrounded by red irritated skin. You can develop one or multiple ulcers which normally can appear on your lips, gums, tongue, inner cheeks or roof of your mouth.

Ulcers should not be mistaken with cold sores which occur on the outside of your mouth around the lips, and which are filled with a fluid that can be contagious.

What causes Mouth Ulcers?

There are a number of reasons that can cause mouth ulcers, the most common reason being biting the inside of your cheek by accident. Other factors include skin rashes in the mouth, certain types of medication, viral, bacterial and fungal infections and certain medical conditions. It is not too difficult to avoid most single mouth ulcers by being careful when chewing your food, avoiding badly fitting dentures, braces, rough fillings and/or a sharp tooth. Consuming hard food or hot food and beverages can cause cuts and burns in your mouth so you should be careful when consuming food.

It is important to be careful when brushing and flossing as being too vigorous can wound your gums which have the potential to develop into mouth ulcers. Be firm but gentle when cleaning your teeth and gums.

Stress is another common cause of mouth ulcers, with there being a connection between your mental health and oral health. For women the monthly menstrual cycle which cases hormonal changes can also cause mouth ulcers with some even experiencing bleeding gums.

Vitamin deficiencies, especially B12 can cause you to suffer frequently from mouth ulcers. So if you find that you are getting mouth ulcers often check you B12 levels, because this vitamin is important to help your body make red blood cells, to keep your nervous system healthy and to help you extract energy from food.

The food you consume too plays a big role in getting regular mouth ulcers. It pays to be aware of what you are eating drinking if you are prone to mouth ulcers.

Acidic fruits – Fruits such as oranges, lemons, limes, strawberries and pineapples are high in acidity and can cause irritation in your mouth and aggravate the gums. This is especially so if you have a sensitive mouth. Add more apples, watermelon and bananas to your fruit diet.

Nuts – While they are nutritious they can also be quite dangerous and cause cuts in your gums which thanks to the amino acid L-Arginine in the nuts cause the cuts to turn into ulcers or sores. If the nuts are salty it causes further complications as the sodium dries your mouth which is not good for your oral health.

Spicy foods – When food is very spicy it can irritate the lining inside your mouth and cause ulcers because spices too have a high acidity and can be considered as acidic food. Hot sauces, jalapenos, spicy curries and chips are some of the goods to avoid if you have a sensitive mouth.

Foods you may develop an allergy to – Basically if you find that when you consume a certain type of food, even in small quantities you develop mouth ulcers, then chances are you are allergic to it. See a doctor for testing if you need confirmation. If it is not severe but uncomfortable note down the foods that trigger ulcers for you and experiment each week so you can determine which foods to cut back on.

Where do mouth ulcers occur?

Mouth ulcers only happen on the inside of your mouth unlike cold sores which can happen on and near the lips as well. Normal mouth ulcers or sores only occur on the soft tissue areas of your mouth such as the inside of your lips, cheeks and your gums. They can even come on or below your tongue, soft palate and the soft muscular area found at the back roof area of your mouth. A good indication that you may be about to get a sore is a slight burning or tingling feeling around the area before it appears. They are usually round or oval in shape with a white or yellow centre surrounded by a reddish hue and come in a variety of sizes from small to large. Unfortunately some can become quite large and painful.

How do you treat Mouth Ulcers?

There is no specific way to treat mouth ulcers as they do not require specialised treatment. Basic mouth ulcer treatment options include over the counter medication like benzocaine a topical anaesthetic and antiseptic mouthwash rinses. Other remedies include options that will help decrease the pain and help to speed up the healing time such as:

  • Rinsing your mouth with a mix of saltwater and baking soda
  • Covering the mouth ulcer with a baking soda paste
  • Putting milk of magnesia on the ulcer
  • Using topical pastes or a damp tea bag on the mouth ulcer
  • Applying ice to the sore

Prevent mouth ulcers by avoiding foods and beverages that are acidic, too hard or too hot. If you have ill fitting braces or dentures or misaligned teeth, visit your dentist and have them remedied as quickly as possible. Ensure that you are getting the proper nutrients and if not be sure to take supplements of folic acid, vitamins B6 and B12 and zinc.

Are Mouth Ulcers a serious condition?

Mouth ulcers are very rarely serious or a symptom of anything more serious but are uncomfortable to live with. Using the remedies above and giving it sometime the ulcer should heal completely. However, there are times when you may need to pay more attention to an ulcer such as if you have an ulcer that lasts longer than 3 weeks, is a constant nagging pain, starts bleeding and will not heal, causes the area to discolour and stay that way or even cause swelling in the neck area which does not reduce then you should seek medical advice.


Preventing mouth ulcers is the best way to deal with this painful yet not harmful oral condition. While it does not require specialised treatment it can take time to heal and be quite painful until healed, so it is best to get over the counter treatment or use the home treatment options listed above. If you are prone to regular mouth ulcers look into the cause and take action to reduce the risk of mouth ulcers and seek the advice of your dentist who will be able to guide your properly.